Recently, a superlattice memory cell provided with layered crystal (GeTe/Sb2Te3) in which a GeTe layer and an Sb2Te3 layer are alternately stacked between two electrodes has been attracting attention. In the superlattice memory cell, by the movement of Ge atoms in the layered crystal, the resistance can be varied.
In a crosspoint memory device using this type of memory cell, a pn junction diode for preventing erroneous selection of unselected cells must be connected to either of the electrodes of the memory cell. For this reason, a film thickness is increased by the existence of the diode. Further, the element characteristics may be degraded by the property variation of the diode.